I don't want to use this blog to advertise my modules, but now I'm very excited about the new versions of Combinator, the css and script bundling and minfying Orchard module: version 1.4 is a quite mature release that can be used in any environment (in a Web Farm scenario too as long as distributed caching is implemented or signals can propagate through the nodes). The alpha release (actually releases: alpha 2 is out now) includes a long awaited feature of image sprite generation! This mean limited support at the time as Combinator currently only understands "background-image" declarations. Background images should be ones with no-repeat or being on a container thats size doesn't exceed the size of the image.
Check Combinator out yourself, and speed up your Orchard site!